Can't assign variables starting with a numeric value in an expression

[tiymat]

Describe the bug:
Variables starting with a numeric component can't be assigned in an expression like other variables (but can be using set.)

I'm not sure if this is a bug or just a language decision but thought I'd raise it for discussion anyway.

Expected behaviour:
Being able to assign variables starting with a numeric component in the same way as any other variable.

Screenshots:

Platform (please complete the following information):

• OS, output from uname -a if supported: 6.9.7-arch1-1
• Terminal Emulator: kitty 0.35.2
• Murex version, output from version --no-app-name: 6.1.8300

Additional context
N/A

[lmorg]

To add to the inconsistencies, it works as an expression if you specify that it is a scalar. eg

» $1foo = 1 + 2

» $1foo
3

The good thing is that, without even looking at the code, I know exactly where the issue is.